3 years ago

List 3 examples of pure substances

Chemistry

2 answers:

ollegr [7]3 years ago

4 0

1. water (H2O) 2. helium (He) 3. iron (Fe)

Brrunno [24]3 years ago

4 0

Table salt, table sugar, and gold.

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I guess A, I am not sure...

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kap26 [50]

Answer:

Explanation:

Efficiency of the electric power plant is $e=1-\frac{T_{2}}{T_{1}}$

Here Temperature of hot source $T_{1} = 450^{o}C=450+273=723 K$

and Temperature of sink $T_{1} = 20^{o}C=20+273=293 K$

Hence the efficiency is $e=1-\frac{293}{723}=0.5947=59.47%$

Now another formula for thermal efficiency Is

$e_{therm}=\frac{Q_{1}-Q_{2}}{Q_{1}}=\frac{W}{Q_{1}}$

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W is the of work done and W = QI -Q2

Hence From $e_{therm}=\frac{Q_{1}-Q_{2}}{Q_{1}}=\frac{W}{Q_{1}}$

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Hence the of heat transferred to the river Is $Q_{2} -W = (100 -59.47=40.53$

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harry potter flips a coin (not magical ) 8 times. He gets heads 1 time. What are the odds that his next flip will be heads? A 10

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C. 50%
Unless the question is saying he only gets heads once, in which case it would be 0%. Or the coin could have 2 heads. Then it would be 100%.
But I'm pretty sure it's 50%.

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The correct answer is :
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